Reflectance and fluorescence parameters of needles of Norway spruce affected by forest decline

Abstract

The reflectance spectrum R(λ) in the range between 366 nm und 780 nm and the fluorescence induction kinetics with a maximum time resolution of 10 μs have been determined from needles of spruce trees with the damage classes S0/S1, S2, and S3. The reflectance values R 660 and R 710 at 660 nm and 70 nm, respectively, the infraredred ratio R 760/R 660, the position λ re of the inflection point of R(λ) at the red edge, the chromaticity point, and the initial and steady-state ratio of the fluorescence intensities at 685 nm and 730 nm are shown to indicate the degree of damage. A quantitative comparison between the data obtained from the reflectance spectrum and the fluorescence measurements demonstrate that both methods provide a similar capability to distinguish between the trees of different damage classes.